A gas turbine combustor employing a premixed combustion system combusts fuel and compressed air that are premixed, and is effective in reducing NOx emission because the fuel concentration is homogenized. Such gas turbine combustor employing the premixed combustion system has been known conventionally (refer to Patent Literatures 1 to 4, for example).
The homogenization of the fuel concentration is effective in reducing the NOx (nitrogen oxide) emission. On the other hand, a mixed state of premixed air in each main nozzle would be substantially the same, thereby causing each main burner to have the same combustion state and a combustor to have the same heat distribution all around in a central axis direction of the combustor. As a result, there would be a certain region in the combustor where the heat quantity is large. Such concentrated heat gives rise to a new problem that the combustion oscillation is more likely to occur.
Now, a gas turbine combustor (a combustor) such as the one described in Patent Literature 5 has conventionally been provided to prevent the occurrence of combustion oscillation. The gas turbine combustor includes: a cylindrical premixing chamber provided inside a casing; a combustion chamber being communicated with the premixing chamber; an air current introduction part for changing the direction of an air current flowing in an air inflow part and introducing the air current into the premixing chamber; a pilot nozzle provided on a central axis of the premixing chamber; and main premixing nozzles extending substantially in parallel with the pilot nozzle and provided at equal center angle intervals in the premixing chamber. The main premixing nozzle includes: a fuel rod in which fuel flows along a central axis thereof; and downstream-side fuel injection pegs attached to the fuel rod at equal center angle intervals and extending outward in a radial direction. Moreover, upstream-side fuel injection pegs are disposed on the upstream side of the premixing chamber at a plurality of stages along the air current direction.